Of course it looks like Glade... It's supposed to be more or less an improved GUI builder (improved compared to Glade). There is no reason to change the box layout model, because it has proven extremely effective.
Stetic looks very interesting to me, as it does not just seem to improve the Glade UI (which is cumbersome at best) but also make it easier to create sane UIs with features like drag and drop with container resizing or automatic padding.
I have no problems with Glade (aside from it's horrid UI), but some tasks can be tedious and repetitive, so any improvement would be welcome.